The present invention relates to a waste oil delivery system and more particularly to a simplified system for delivering waste oil to a burner or heater which may be located a long distance from and elevated well above an oil reservoir.
Numerous varieties of heaters or burners are known, and these include heaters and burners which utilize the combustion of oil to produce heat. Typically, the oil is delivered from an oil source or reservoir, such as a tank, to an orifice in a nozzle located adjacent to or in a combustion chamber. The nozzle and the orifice may mechanically atomize the oil (a so-called "hydraulic combustion system") and/or admix air to aerate it (a so-called "air atomizing combustion system") to produce an aerosol thereof. In either event, the oil, now mechanically broken up into micro-globules, is directed into the combustion chamber, where it is burned to produce heat.
Oil burners and heaters are often capable of combusting fuel oils ranging from No. 1 fuel oil--a volatile, distillate oil--to No. 6 fuel oil--a high-viscosity fuel--to waste oils. Prior art fuel oil delivery systems have utilized a single pump, located physically near the burner or heater. The low side of the pump is connected to a line to which the pump applies a negative pressure (about 10-12 inches of mercury) to pull the fuel oil into the pump. Thereafter, the pump transmits the oil to its high side for subsequent delivery through a delivery line to the nozzle or its orifice. A practical limit on the maximum distance between the fuel reservoir and the low side of the pump is imposed by the physics of lifting liquids by negative pressure. This practical limit is a head lift of about fourteen feet. Thus, the use of single pump prior art fuel oil delivery systems is limited to residences and commerical buildings of moderate height (where the tank is at or near ground level) or to the ground level of a building (where the tank is buried). Higher buildings or deeper tank depths require multiple, or booster, pump systems, or multiple tanks and delivery systems periodically spaced throughout the levels of the building.
Thus, one hallmark of prior art oil delivery systems is a reliance on "pulling" fuel oil to the burner or heater.
The type pump most often found in prior art oil delivery systems typically regulates its output pressure to a selected value by means of an internal or adjunct pressure regulator. A relief valve or similar relief device, may also be provided to bypass excess oil, that is, oil in excess of that required to maintain the selected output pressure, back to the reservoir. The output pressure at the high side of the pump is usually with the range of 75-300 pounds per square inch where the oil is non-waste oil which is burned in a hydraulic combustion system. Where the fuel oil is waste oil or other oil burned in an air atomizing combustion system, the pressure of the oil at the high side of the pump is maintained by the pump at about 10 pounds per square inch.
The high side of the pump in a prior art fuel oil delivery system moves pressure-regulated fuel oil through the line connected thereto to the nozzle. The amount of pressure regulation or bypassing which occurs at the pump varies at the viscosity of the oil. Viscosity, in turn, is dependent on the inherent characteristics of the fuel oil (e.g., its chemical make-up) and the temperature thereof. Because of these variables, the flow rate of the fuel oils to the nozzle is difficult to control by pressure regulation.
The range of pressures which may be experienced at the high side of the pump and the difficulty in controlling the flow rate of the fuel oil to the nozzle has led to the use of pressure regulators in the high side line between the pump and the nozzle. Such regulators maintain the pressure of the fuel oil delivered to the nozzle within a range of about 3 to 5 pounds per square inch. Typically, the regulator is "automatic" and regulates the upstream pressure of the fuel oil as the pressure of the oil delivered to the nozzle varies.
In order to "match" the amount of oil delivered to the nozzle and the requirements of the particular combustion zone with which the nozzle is used, the size of the orifice in the nozzle may be appropriately selected.
Thus, another hallmark of prior art fuel oil delivery systems is the reliance on pressure regulation and orifice size to control and regulate the flow rate of fuel oil to the nozzle.
The above-described limitation on the distance from which, and the height to which, fuel oil may be delivered, the difficulty in controlling flow rate of fuel oil to a nozzle, and the need to rely on pressure regulation and orifice site to achieve desired oil flow are factors adversely affecting the applicability and economy of present fuel oil burner and heater systems. An object of the present invention is to eliminate or ameliorate these factors by the use of a simple, economical fuel oil delivery system.